Compound hydraulic brake compressor and the like



Sept. 17, 1946.

A. HULL-RYDE 2,407,957

COMPOUND HYDRAULIC BRAKE COMPRESSOR AND THE LIKE Filed June 25, 1943 2 Sheets Sheet 1 R? a W N Q m in Q i\ N N o N m g h h g a *ze g v IN V EN TOR.

ARTHUR HULL-FY05.

4;. ATTORNEKi Sept. 17, 1946. uL 2,407,957

COMPOUND HYDRAULIC BRAKE COMPRESSOR AND THE LIKE Filed June 25, 1945 2 Sheets-Sheet 2 N R \I' u E? R Q A? G Pr 1 0 W an \9 N Q N 9/ V10 N I I a U k a -53 IN V EN TOR. A R TH UR HUL. u-Rro E.

'fi; ATTORNEKS.

Patented Sept. 17, 1946 COMPOUND HYDRAULIC BRAKE COMPRESSQR AND THE LIKE Arthur Hull-Rydc, Bayside, N. Y., assignor of onefourth to Arthur Wilde, Bayside, and one-half to Martin V. Groves, Brooklyn, N. Y.

Application June 25, 1943, Serial No. 492,281

7 Claims. (01. so -54.6)

My invention relates to compound hydraulic brake compressors or thelike, and more particularly to a valve structure for controlling the operation of said compressor or for controlling the pressure between a low pressure side and a high pressure side.

Since the invention has been usefully employed in compound hydraulic brake compressors, sometimes called compound master cylinders, it will be described in such an embodiment by way of illustration.

In structures of this character, the operation comprises in general two stages; the first stage representing the low pressure stage and the second stage the high pressure stage. In passing from one stage to the other, the operation is controlled by a high pressure or unloading valve which comes into operation at a predetermined pressure. It is desirable in such structures to have this valve operate in such a way that the carry-over from one stage to the other he effected with a smooth action so that the change from simple to compound action may be brought about without any noticeable surge in the system. This is particularly important where the cornpressor is utilized to deliver an ultimate relatively high pressure.

' Additionally, in compressors or compound master cylinders of the type disclosed, the valve serves as a hydraulic coupling between th primary and secondary pistons causing them to move to gether as one unit during the first or low pressure stage and permitting relative movement between said pistons during" the second or high pressure stage; and in such a structure, it is likewise desirable thatthe coupling and uncoupling of the two pistons be efiected smoothly and Without appreciable jerk.

. The present invention is in the general nature or an improvement over that disclosed in the copending application of Martin V, Groves, Serial No, 463,165, filed October 2%, 1942, now Patent No. 2,343,901, for Compound hydraulic compressors both as to structure and operation.

An object of the present invention is to provide an improved high pressure or unloading valve structure providing a smooth change-over from low pressure to high pressure.

Another object of the invention is to provide an improved valve quickly without undue jerk or surge and which will positively remain open at all pressures above that at which it is designed to open.

Another object of the invention is to provide a simplified valve mechanism permitting rockstructure which responds ing or successiverapid out losing. pressure.

Further objects and advantages of the invention will more fully appearlfrom the following I description taken in connectionwith theaccompanying drawings Which show, by way of exam ple, present preferred embodiments of --the invention.

The invention consists in the novel features, arrangement, and combination .Of parts .embodlied by way of example inthe mechanism hereafter described as illustrative of th present preferred forms of the invention, and the'invention will be more particularly pointed out in the appended claims.

Referring to the drawings:

Fig. 1 is a longitudinalsectional view illustratingthe compressor unit embodying the invention; and 1 Fig. 2 is a longitudinal cross-sectional View, on an enlarged scale, of a part of the unit disclosed in Fig. 1, illustrating a modification there- Since the invention relates more particularly to a valve mechanism and arrangement, only such portions of the remaining structure of the compressor unit will be described as necessary to show the full and complet relationship of the parts. i r V Referring more particularly to Fig. 1,,a primary cylinder is designated as l, and positioned therein for reciprocal movement is a ,primary piston 2 provided with spaced apart heads comprising sealing cups 3 andA. The piston is somewhat reduced in diameter intermediate the cups 3 and 4 to provide an annular chamber 5 which is in constant communication with the reservoir E through a port 7. Th reservoir 6 is provided with a further port 8 which is in communication with the space 9 provided in the cylinder I forward of the head 3 when the piston is in retracted position, as indicated in the drawings. The space 9 provides a pressure chamber adapted to be. placed in communication, as by an outlet It, with the pressure line,.such as a brake system, and egress and ingress is controlled by suitable cheek valvemechanism designated in its entirety as It, A plurality of ports l2 provide passage of fluid from the annular chamber 5 to the pressure chambers to provide for bleeding the system, and the sealing cup 3 prevents revers passage of the fluid. from the chamber 9 into the chamber 5. The valve I is held in place by a spring l3 which is seated on a spring plate 13', resting in a shoulderprovided in the cylinactuating impulses with- V der l, and having suitable openings for the passage of fluid from the chamber 9 to the valve II. In the present embodiment, the primary piston 2 is retracted by a spring (not shown) which may be on th exterior of the unit, such as on the brake pedal or actuating rod.

The primary piston 2 is provided with an axial bore [4 which serves as a secondary cylinder within which is provided a secondary piston l5 provided with a head comprising a sealing cup l6. The secondary piston I5 is provided with an axial bore I5 in which is seated the rear end of a retractile spring I! whose forward end is in engagement with an annulus cup l8 which is seated against the forward head of secondary cylinder Hi, i. e. on the primary piston 2. V A priming valve, designated in its entirety as I9, is disposed within the cup [8 for controlling the passage of fluid between the high pressure cylinder [4 and the reservoir 6 by way of passages 20, the annular space 5 and the opening 1. The priming valve 19 is a one-Way valve serving to take fluid from the reservoir 6 upon retractile movement of the secondary piston I5 and to close upon forward actuation of said piston.

The secondary piston is somewhat reduced in diameter rearwardly of its forward end so as to provide aspace 2! which is in communication with'the'space 5 through a series of ports 22. To the rear of the sealing cup 4 and within the cylinder. I, there is provided a chamber 23, which for purposes of convenience will be referred to as the primary chamber.. Between this chamber 23 and the space 2|, there is provided a checkvalve designated as 24, so constructed and arranged that in the retracted position of the parts as indicated in Fig. 1, the valve is open, placing the space 2| and chamber 23 in communication; and during the actuation of the compressor, the valve is closed so as to prevent passage of fluid from the chamber 23 into the space 2!. The chamber 23 extends rearwardly into a reduced bore 25, forming a rearward extension of the cylinder I, and in communication, by way of a port 21, with an axially extending cylindrical bore 28 in communication withthe secondarycylinder [4 by way of the bore l5. The flow of fluid between the small cylinder l4 (i. e., high pressure side) and the large cylinder 23 (i. e., low pressure side) is controlled by the structure to be more particularly described following.

A valve plunger 29 is slidably disposed in the bore. 28 with a relatively fluid-tight lit; and is provided with an annular port groove 30 in communication with the bore 28 by means of radial passages 3! and an axial passage 32. The plunger 29 is resiliently held outwardly, so that the ports 21--30 are out of register, by means of a helical compression spring 33 disposed between the inner end of the plunger 29 and an annular shoulder 34 provided between the bore 28 and bore I 5. In this position the valve is closed. Means to open the valve will now be described.

The outer end of the plunger 29 is provided with a piston head 35 of larger diameter than the forward end of the plunger 29 and bore 28, and the piston head 35 is disposed in a cooperating cylinder 36, formed as an enlarged continuation of the bore 28'. In the closed position of the valve, the piston 35 separates the cylinder 36 into a closed rear fluid chamber 31 and a forward chamber 38 which is vented by means of a port 39 to atmosphere. It is important that this chamber 38 be vented to a pressure lower than that of the low pressure side; but

4 instead of being vented to atmosphere directly, the port 39 may, if desired, be vented to the reservoir 5 and thus avoid possible leakage of any fluid which may escape from the bore 28 past the plunger 29 into the chamber 38. The fluid chamber 3'! is placed in communication with the bore 28 by means of a passage 49, one end of which is in communication with the cylinder chamber 31 and the other with the bore 28 by way of the passage 32. It is to be noted that the passage 49 is of relatively smaller size than the passages 32-3l and ports 38-4! and of sufficiently small diameter to restrict the sudden passage of the fluid required to move the valve from its closed to its open positions. With a given strength of spring 33, by enlarging the diameter of the passage 49, the valve would open at alower than normal pressure on'a fast brake application; and, conversely, by reducing the diameter of passage 49, the valve would open at a higher than normal pressure. The correct size of this passage is such that it offers suflicient restriction to the passage of fluid from the bore 28 into the chamber 31 to enable the valve to open at substantially the same pressure on fast as on slow application. The spring 33 must be of sufficient strength to return fluid through the passage 49.

It will be seen from the foregoing that the forward head of the plunger 29 and the rear of the piston 35 are subjected to the same degree of fluid pressure. However, since the piston 35 has a greater area than the head of plunger 29, there will be a pressure diflerential urging the plunger 29 forwardly, and at a. predetermined pressure the spring 33 will be overcome and the plunger moved to the end of its forward stroke, as limited by engagement of piston 35 with the bottom of its cylinder 33. This will place the valve parts 21-39 in register and the valve will be fully open and the compound pressure actuation then takes place. The pressure at which this takes place, therefore, is determined by the difference in area between the plunger 29 and the piston 35 and the resistance of the spring 33. One feature of this structure is that the chamber 38 is never exposed to substantial pressure. Once the valve is open, it can not close until the pressure has dropped to or below the point at which differential in pressure on the plunger 29 and piston 35 caused the valve to open, i. e., as soon as this differential is less than the force exerted by the spring 33, the valve will be closed and not before. Once the valve opens and the predetermined pressure is maintained in bore 28 (and cylinder I4), the passage 49 becomes inoperative and does not affect the speed at which the brakes can be applied since fluid for this purpose passes through the passage '32 and ports 39-21 which may be of substantial diameter.

' Modification In cases where it is necessary to have several very rapid applications in quick succession, it may be desirable to avoid a restricted flow of fluid from the chamber 31 back into bore 28, to thereby permit a given size spring 33 to more quickly return the valve to closed position. The inability of a quick return of valves for like purposes to closed position has proven a great difficulty heretofore in installations where quick successive applications are of importance. In Fig. 2 I have shown a modified valve plunger which readily provides this desirable quick return,

without detracting from the other valuable features of the invention.

It will be understood that the modified valve rep-laces that of Fig. 1, and only uch parts of the entire device will be illustrated as may be useful in understanding the modified valve structure. The structure of Fig. 2 which is identical with Fig. will be identified by the same numerals used in Fig. 1 for like parts with an added a suflix.

Referring more particularly to Fig. 2: The valve plunger is designated as 50 and is provided with a. port 5! adapted to be placed in communication with the high pressure side (a 28a) by means of radial passages 52 and an axial passage 53; the port 5! being adapted for cooperation with the port 21a. The passage 53 is somewhat larger than (the corresponding passage 32 of Fig. l and terminates in a passage 54, somewhat larger than the corresponding passage 49 of Fig. l, for commtmication with the chamber Sla in which a piston head 55 is adapted to be positioned. Adjacent the passage 54, the passage 53 is provided with a conical valve seat 59 for a cooperating valve head 5'5 resiliently held thereagainst by means of a light helical compression spring 58 whose forward end is seated on a screw ring 59 axially held, as by screw threads, within the passage 53. The valve head 5! is provided with a restricted passage 69 which corresponds in size and function to the passage til of Fig. 1.

It will be seen that with the valve 5'! held on its seat 55 the passage 69 restricts the flow of fluid in a direction from the bore 28a into the chamber Sta; while in a reverse direction of flow the valve head 5'! moves against it spring 58 to raise from its seat 56 and thereby provide for a more rapid flow of fluid from the chamber 31a into the bore 28a.

Operation With the parts in the position shown in Fig. 1, the primary piston 2 being held in retracted position by suitable means (not shown), and the secondary piston being held in retracted position by the spring I1, and the valve plunger 29 being held in closed position by its spring 33; the outlet opening it being attached to the fluid line of the device or devices to be actuated, and the entire system being supplied with the requisite fluid, the device operates in the following manner: Manual pressure is exerted upon the outer end ll of the secondary piston l5, as by means of suitable connections thereto, preferably including .the ball or swivel connector 42. At this time, fluid is trapped within the secondary cylinder M between the piston 55 and the priming valve l9 which is closed, thereby coupling the piston IE to the piston 2 for unitary movement. As the piston 2 is advanced, the ring 3 closes the port 8 to the reservoir 6 and fluid is displaced from the chamber 9 through the plate l3 and the valve I I outwardly through the outlet l0 into the main line of the device or devices to be actuated. Upon predetermined pressure being attained in the chamber 9, the corresponding pressure is of course present in the secondary cylinder [4, and as this predetermined pressure is exerted also within the bore 28, it is communicated through the passage 32 and the restricted passage 40 into the closed cylinder chamber 3?, which being of a larger area than the opposite end of the plunger 29 causes the plunger 29 to move forward against the spring 33 thereby compressing the samethe chamber 38 being vented through a, por-t39-- and when the member 29 has reached the forward position of its stroke, the port 30 comes into register with the outlet port 21, thereby permitting the high pressure fluid from the cylinder Hi to pass through the bore 15', the bore 28, through the passages 32 and Si outwardly through the ports 39-2! into the annular chamber 25 and primary cylinder 23. At this time, the valve 23 is closed, due to the pressure on the rear of said valve which was released from open position by the forward movement of piston 15. The pressure is thereby compounded by being displacedfrom the small or secondary cylinder l 5 into the large or primary cylinder 23, to thereby continue to move forward under compound fluid pressure the piston 2 which as above described displaces fluid from the chamber 9 out through the opening l9. As previously pointed out, the restricted passage to into the chamber El controls and limits the volume of fluid passed into the chamber 3? so that the valve is caused to gradually open under the differential of pressure between the small piston head of the plunger 29 and the larger piston head 35, the differential thus created being sufficient to overcome the resistance of the spring 33.

When the pressure in the secondary cylinder M which is exerted through the bore 28 on the plunger 29 is relieved by removing manual actuating pressure from the end M of the piston l5, the pressure of fluid in the chamber 31 is removed and the spring 33 returns the plunger 29 to the rear. It is noted that in the embodiment of Fig. 1, the restricted passage ifl also serves as a check on the return or fluid from the chamber 37 to the bore 29. However, where it is necessary for a much quicker return of the valve to closed position, such as where rapid successive actuation is necessary, the modification shown in Fig. 2 may be utilized, and in such event when the pressure is reduced to or below the predetermined pressure, the valve head 51 moves to the left compressing the light spring 58 and the flow of fluid is not restricted by the small opening 66 but there is provided a much freer passage through the valve sea 55 and past the open valve member 5'5, thence through the large bore '53 into the bore 23a.

Upon the return movement of the piston l5, the valve 24 is opened permitting fluid to pass from the primary cylinder chamber 23 past the valve 24 through the passages 2i into the annular passage 5 and out through the opening 1 into the reservoir 6. Likewise as the spring ll retracts the piston l5, the one-way priming valve i9 is pulled from its seat by suction in the cylinder l4 permitting fluid to pass through the passage 29 from the annular chamber 5 which, as above described, is in communication with the reservoir .6 by way of the opening 7.

In either of the embodiments of Fig. l or 2, the venting of the space 38 in front of the piston 35, as by means of the-port 39, permits a more accurate calibration of the valve than would be the case if the pressure moving the plunger 29 to the open position of the valve had to work against the pressure in the annula space 25 or other operative pressure chambers of the system.

Having thus described my invention with particularitywith reference to preferred forms, and having described and referred to certain modifications, it will be obvious to those skilled in the art, after understanding my invention, that various changes and other modifications may be made-therein without departing from the spirit and scope of my invention, and I aim in the appended claims to cover such changes and modiflcations as are within the scope of the invention.

What I claim is:

1. A movable valve structure comprising a valve body having a high pressure inlet bore provided with an outlet port, a valve carried by said body and movably disposed in said bore to open and close said port responsive to predetermined fluid pressure exerted on said valve, a valve piston movable with said valve and disposed within a hollow cylinder provided on said body, spring means urging said valve to closed position and said piston rearwardly in said cylinder, said piston dividing said cylinder into a front compartment and a rear compartment which constitutes a fluid chamber, said valve being provided with a continuously open restricted fluid passage from said highpressure inlet bore to said fluid chamher to move said Valve to open position against said resilient means upon predetermined pressure being reached in said high pressure bore, means providing an enlarged fluid passage'in the reverse direction from said fluid chamber to said high pressure bore to release said resilient means upo the pressure in said high pressure bore falling below a predetermined value, and means for venting said front compartment.

2. A valve structure having outlet and inlet chambers, valve means interconnecting said chambers comprising a body providing a hollow cylinder closed at one end and a bore smaller than that of the cylinder extending from the oth- 7 er end of said cylinder and in communication with said inlet chamber, said body also providing a first port extending outwardly from said mall bore and in communication with said outlet chamber, a valve plunger having piston head in said cylinder and a relatively smaller head in said bore, said plunger being provided with a restricted passage interconnecting saidcylinder and inlet chamber and with a second port in communication with said restricted passage and positioned for cooperative registration with said first port, resilient means urging said plunger outwardly to disconnect said ports for closing the fluid passage between said inlet and outlet chambers, said plunger being movable inwardly against said resilient means by a predetermined fluid pressure exerted on said piston head from said inlet chamber to thereby place said ports in register and to open the fluid passage from said inlet chamber to said outlet chamber, and-means for venting said cylinder forwardly of said piston to a pressure lower than that of said outlet chamber.

3. A movable valve structure comprising a valve body having a high pressure inlet bore provided with an outlet port, a valve carried by said body and movably disposed in said bore to open and close said port responsible to predetermined fluid pressure, a valve piston integral with said valve and disposed within a hollow cylinder provided on said body, said cylinder having a, rearwardly disposed head between which and said piston a close fluid chamber is provied and having a relief port disposed forwardly of said piston, spring means urging said valve to closed position and said piston rearwardly in said cylinder, said piston and valve being provided with a fluid passage placing said fluid chamber in communication with said inlet bore, relief valve means disposed in said passage and providing continuously open restricted passage for the flow of fluid between said inlet bore and said fluid chamber and an enlarged opening for the flow of fluid in the reverse direction; whereby upon a predetermined pressure being reached in said inlet bore said piston is moved forward against said sprin means under control of said restricted opening and said valve is opened to thereby place said inlet bore and outlet port in communication, and upon the pressure in said inlet bore falling below said predetermined value said piston is relatively more freely returned rearwardly by said spring means and said valve i relatively rapidly closed thereby disconnecting said inlet bore and outlet port.

4. A valve structure comprising a pressure chamber having an outlet port, a reciprocable valve member for opening and closing said port, resilient means for yieldably holding said valve member in closed position, a piston for driving said valve member to open position against said resilient means, a cylinder within which said piston is disposed and providing therewith a closed cylinder chamber on one side of said piston for actuation of said piston, said cylinder on the opposite side of said piston being provided with a relief port, said piston and valve being provided with a passage in communication with said pressure chamber and said cylinder chamber, and valve means in said passage providing when closed a continuously open restricted fluid passage therethrough into said cylinder chamber and providing when open relatively free passage therethrough from said cylinder chamber into said pressure chamber.

5. A valve structure comprising a pressure cylinder having an outlet port and an inlet opening, a larger cylinder in series with said pressure cylinder, a reciprocable valve member comprising a piston disposed in said pressure cylinder and a larger piston disposed in said larger cylinder and providing therewith a closed cylinder chamber on one side of said larger piston for actuation of said valve member, said larger cylinder on the opposite side of said larger piston being provided with a relief port, said valve member being provided with a fluid passage having one end in communication with said pressure cylinder and the other end being of smaller cross-sectional area and in communication with said closed cylinder chamber, said valve member also being provided with a valve port disposed for cooperation With said outlet port and in communication with said one end of said passage, and resilient means for yieldably holding said valve member in a direction toward said closed cylinder chamber and said ports out of register.

6. In a compound hydraulic compressor of the character wherein a secondary piston is operable to produce pressure fluid in a secondary chamber from where it is passed to a primary chamber through an axial bore and an outlet port in 'said piston, the combination with said secondary piston providing a valve piston cylinder in liquid communication with said bore and of larger diameter than said bore, of a reoiprocable valve member comprising a piston valve disposed in said bore and a valve piston of larger diameter operatively disposed in said valve piston cylinder and providing therewith a closed cylinder chamber on one side of said valve piston for actuation of said piston valve in one direction, said valve piston cylinder on the opposite side of said valve piston being providedwith a relief port, said piston valve being provided with a passage interconnecting said secondary chamber with a valve port disposed for cooperative registration with said outlet port and with a continuously open restricted fluid passage between said secondary chamber and said closed cylinder chamber, and resilient means for yieldably urging said valve member in a direction toward said closed cylinder chamber and said ports out of register, said restricted passage being of such size as to effect opening of the valve at substantially the same pressure in said secondary chamber on fast as on slow operation of said secondary piston, and said resilient means being of sufiicient strength to return fluid from said closed cylinder chamber to said secondary chamber.

'7. A valve structure comprising a pressure cylinder having an outlet port and an inlet opening, a larger cylinder in series with said pressure cylinder, a reciprocable valve member comprising a piston disposed in said pressure cylinder and a larger piston disposed in said larger cylinder 10 and providing therewith a closed cylinder chamher on one side of said larger piston for actuation of said valve member, said larger cylinder on the opposite side of said larger piston being provided with a relief port, said valve member being 

